Apparatus for testing packing materials



Sept.. 23, igz

R. w. JUSTICE 2,611,263

APPARATUS FOR TESTING PACKING MATERIALS Filed Oct. 13, 1949 me/who@ RAYMOND W. JUSTlCE Patented Sept. 23, 1952 APPARATUS FOR TESTING PACKING MATERIALS i Raymond W. Justice, Youngstown, Ohio Application october 13, 1949, serial No. 121,187

s claims. (o1. `vs 9) This invention relates to testing apparatus and more particularly to apparatus for determining the frictional resistance to sliding movement created by fluid-tight packings in machine elements such as hydraulic pistons, for example.

The efiiciency of fluid-sealing packings is determined not only bythe ability of the packing to contain the applied fluid pressures but also by the amount of`frictional resistance to movement of the relatively movable parts resulting from the presence ofthe packing. It is therefore desirable to be able to determine and predict the extent of frictionalresistance which can be expected from the'v installation `of different kinds of packings in hydraulic and other machinery.l Itis accordingly the primary object of the invention to provide a practical apparatus which is operative to accurately indicate relative frictional resistances set up by diierent packing materials and acting under widely varying operational pressures.

A further object of the invention is the provision in apparatus of the kind mentioned above of an improved arrangement whereby all factors other than the friction factorsupplied by Vthe packing being tested are automatically cancelled out so that a direct comparative reading of the frictional resistance created by the packing is made possible. f

The above and other objects and advantages of the invention will become apparent upon consideration of the following detailed, specification and the accompanying drawing wherein there is disclosed a preferred embodiment of the invention. Y

In the drawing' Figure l is ajside elevation, partly in section, of a testing machine constructed according to my invention; and

Figure 2`is a fragmentary longitudinal section,

on an enlarged scale, of the apparatusof Figure 1.

The apparatus illustrated comprisesan internally honed cylinder vIII having end members II and I2 which are secured to the cylinder I0 byl It should be noted that the plug I1 extends outwardly and is integral with a square `boss I8 ex'- tending `outwardly from the face of the p-art I5 and formed integrally therewith. The outer periphery of the piston part I5 is recessed inwardly' from the face thereof as shown at I9 to receive a packing assembly which may consist of rigid end rings 20 and 2l of bronze, for'example, and in` -termediate chevron packing rings 22 of leather, for example. A similar recess' 23 is formed in the outer periphery of the piston part I6 and this latter part is also formed with an axial recess 24 to receive the outer end portion of the boss I8.

To retainv the packing ring assemblies in the recesses I9and'22 and to supply fluid pressure thereto in axial thrust relation I employ a spacing washer 25 which' is centered over the boss I8 and which is provided with a pluralityof interconnected radial and axial bores 26 and 21, respectively. The ring or washer 25 may be constructed ofeither bronzexor steel and its outside diameter is somewhat less than the internal diameter of the cylinder II) so as not to bear thereagainst. This is'also vtrue of the outer diameters of the parts I5 and I6. Y

To conduct iiuid pressure into the passages 26 and 21 of the washer 25 the rod I3 and piston part I5 are provided with a centrally disposed bore 28 which terminates in a radially extending opening 29 in whi-ch is attached a fitting 3i)` con l nected, in-turn, to a flexible supply conduit (II.

Radial passages are formed in the boss I8 to connect the bore 28 with the bores 26 in the washer 25j and it should be apparent that fluid pressure supplied by the conduit 3| 'will enter through passages 28, 26 and 2I, in sequence against the 'fiat bases of the rigid rings 2| of the packing assemblies mounted on the piston whereby these assemblies will be subjectedv to,

axially applied fluid pressures in substantially Y the same manner as fluid pressures are applied II'I. In axial alignment with this bore 28 is a bore 32 in rod I4 and piston part I6 terminating in a radially extending opening 33 to which is attached a pressure gauge 34.r In this manneran accurate indica-tion of the uid pressure actually applied to the packing assemblies on thel piston may be obtained. n

Extending outwardly of vthe end housing I2 is 'a tube 35 having a, longitudinally' extending 19# there@ i0. Slidablr recare; weer 11.09195 The part 36 is provided with a threaded bore to receive a screw-threaded rod 31 which is rotatable in the tube 35 so that upon rotation of the rod 31 the hook 36 will be drawn along the tube 35 as will be understood. A hand crank 38 is keyed in the outer exposed end of the rod 31 whereby the latter may be rotated. Detachably secured to the exposed end of the piston rod I4 outwardly of the passage 33 is a hook-line member 39 adapted to be' interconnected with the jack hook 36 by a dynamometer 40 having a connecting link 4| at each end thereof. The dynamometer 40 is a conventional instrument arranged to give a direct reading on its dial of the pulling force exerted on the two connecting my invention to make the apparatus portable t,

and, .in practice, the supply unit may be in the form of a combined reservoir, pump and valve assembly as shown at 42. Such combined apparatus is conventional in the art and includes a pump, not shown, to which isA connected an operating lever 43, the pump having an outlet which in the present case is connected to the exible conduit 3|. The uid pressure supply unit further includes a valve, also not shown, having an actuating lever 44 which upon being depressed is operative to connect the conduit 3| with the reservoirin the unit 42 whereby the uid pressure in the conduit 3| may be relieved as desired. In accordance with usual practice a suitable check valve is associated with the outlet of the pump in unit 42 to maintain the desired pressure built up in the test cylinder by manipulation of the lever 43.

' When itis desired to test any particular style 2,611,263 e. I Y

of packing or kind of packing material specimens of the proper size to fit inthe recesses I9 and 23 ofthe piston parts I 5- and I6 are first either procured. or prepared. The test apparatus is disassembled by removing` the fitting 30 and the end housing II` which allows the endhousing II and cylinder I0 to be removed, thus exposing the piston of the apparatus. The piston may now be dis-assembled by unscrewing the part I5, thereby' exposing. an axial end of each of the recesses I9' and 23A to allowY the packing ring assemblies to to be tested to be properly mounted on the piston parts I5 and I6. The piston is now re-assembledv with the spacing washer.' 2 5in proper position. between the two packing' ring assemblies. The cylinder I0, end housing II and tting |3 will now be re-assembled so the testv can proceed. At the start, the piston I5, I6 may be moved toA the left end ofthe cylinder it, as viewed in Figure l. By means of the pump in unit 42 fluid pressure of a desired value is applied to the packing assembliesv to be tested and upon the pressure reaching a desired value as indicated by the meter 34 the crankSS is actuated to draw the piston and packing assembly longitudinallyV through the cylinder I0 and the force required to do so is measured by the dynamometer' 40. This force measurement gives an'accurate indication lof the frictional resistance caused by the packing assemblies under' thev particular.' fluid pressure applied' since` the frictional resistanceA at the other sliding` joints ofthe apparatus'is 75 negligible due to the loose tolerance provided between the cylinder and piston assembly and between the end housings I I and I2 and the rods I3 and I4, respectively. The axial length of each of the two packing ring assemblies is that recommended for the particular diameter of the cylinder of the test apparatus so that the force indicated by the dynamometer 40 will be twice the frictional' resistance whichcan'bef expected from one of the packing ring assemblies when installed in a conventional cylinder and piston combination. By taking comparative readings at different applied iiuid pressures and With different packings and packing materials it is possible to make a complete analysis of different materials under widely varying applied fluid pressures, as will be understood.

In certain types of packing the frictional resistanee-to sliding movement may be greater in one direction than in the other or opposite direction and it is therefore not possible' to get a direct reading of the frictional resista-nce simply by halving the force indicated by the dynamometer. and in'such cases the apparatus allows `me to kinstall a packing assembly of known and proven friction value on one part of the piston assembly while the packing to be tested is installed on the other part of' the piston assembly. By subtracting thefknown value from the dynamometer reading the frictional resistance of the packing under test can be readily determined and since the piston and rod assembly including the partsV I 3', I4, I5 and i6 are readily reversible' asa unit with respect to the cylinder, readings can readily be obtained for either direction of movementof the packing assembly under test.

l'. also contemplate. that the central bosses on the'end members and I2 of the cylinder assembly may be enlarged and recessed in a manner analogous to the structure shown in Figure 1 of my copending application S. N. 121,188 filed October 13, 1949, whereby the apparatus of the inventionl may also be rendered suitablefor testingpiston yrod packings in'addition to piston packings. In such use-of the modified apparatus either one or both of` the packing assemblies on the pistonr would bey omitted to enable the full application of the desired pressure against either or both of the piston rod packings mounted in the end members II 'and I2.

An important feature of the apparatus of4 the invention is the ability to maintain constant the iiuid pressure applied even while the piston is in motion and while a continuous reading of the dynamometer 4B is being taken. Thus, not only is itpossible to measure the starting friction but also the operatingfor. moving friction of the packing being tested.

fIhe above specically describedA embodiment ofthe invention should be. considered as illustrativeV only as many changes may be made thereinwithout departing fromlthe spirit or scope of thev invention. Reference should therefore be vhad to the appended claims in determining the` scopev of the invention.

I claim? e Y 1. In apparatus for measuring the frictional resistanceftc sliding movement of piston-type of packings comprisingin combination a cylinder, apiston slidable in said cylinder and having an outwardly extending pistonl rod, a pulling device adapted to be moved outwardly along the axis of said rod, a dynamometer interconnecting said pulling device" and said rod and operative to measure the forcerequired toY move" said` ro'd :and

piston, said piston having an annular recess to receive a packing ring assembly to be tested, fluid passages in said piston to conduct fluid under pressure to one axial face of said packing ring assembly, and means to conduct fluid under pressure into said passages.

2. In apparatus for measuring frictional resistance to sliding movement of piston-type packings comprising in combination a cylinder, a piston assembly slidably mounted in said cylinder comprising a pair of separable members, each having an annular recess to receive a packing ring assembly to be tested, said recesses extending axially outward from the inner adjacent faces of said members and terminating in anges adjacent the outer ends of said members, a spacing washer carried vby said piston and separating said recesses, said spacing washer having radial and axial passages to conduct fluid pressure to the inner faces of the packing assemblies contained in said recesses, means to conduct uid under pressure into said passages, means to move said piston axially in said cylinder, and means to measure the force required to move said piston in an axial direction.

3. In apparatus for measuring frictional resistance to sliding movement of piston-type packings comprising in combination a cylinder, a piston slidable in said cylinder and comprised of two separable members each having a rod extending outwardly therefrom and each having an annular packing-ring-receiving recess extending axially outward from the inner face thereof and terminating at a flange, centrally disposed passages in said rods and members in communication with each other, means in said piston to conduct iiuid pressure from said passages onto the inner axial faces of packing ring assemblies mounted in said recesses, the passages in said rods having terminals positioned loutwardly of said cylinder, a flexible conduit connecting with the passage terminal on one of said rods to conduct uid pressure thereinto, a pressure gauge mounted on the other of said rods and connecting with the passage terminal thereon, means to slide said piston in said cylinder, and means to measure the force required to slide said piston in said cylinder.

4. In apparatus for testing ring-like packing materials a piston comprising a plug-like member having an annular packing ring receiving recess in its outer periphery extending axially inward from one end thereof, a boss on said member extending centrally and axially outward of said end and adapted to mount a separating washer, a separating washer on said boss, a screw-threaded extension integral with and projecting centrally and axially outward of said boss, a second plug-like member having a threa ed bore to receive said threaded extension and having an annular recess in its outer periphery to receive a second packing ring assembly, said last mentioned recess being open axially to said washer whereby upon assembly of said piston said washer is operative to separate and retain said two packing ring assemblies, and a piston rod connected with one of said members.

5. Apparatus according to claim 4 further characterized in that said piston rod and connected member are provided with a centrally disposed bore for the passage of fluid pressure, said boss and washer having radially disposed passages therein in communication with said rst mentioned passage, and said washer having axially disposed passages in communication with said radial passages whereby uid under pressure may be brought to bear against the adjacent end faces of said packing ring assemblies.

6. In apparatus for measuring the frictional resistance to longitudinal sliding movement of piston-type packings the combination of a cylinder, a piston assembly slidable longitudinally in said cylinder and having a pair of rigidly interconnected piston-like parts spaced longitudinally to define an annular space therebetween, means on one of said piston-like parts to receive a piston-type of packing to be tested with the fluid pressure existent in said annular space acting on an axial end of said packing in one longitudinal direction while said other piston-like part restrains longitudinal movement of fluid from said annular space in the opposite longitudinal direction, means forming a fiuid passage communieating with said annular space whereby fluid under predetermined pressure may be supplied to said annular space, means to move said piston assembly longitudinally in said cylinder, and means to measure the force exerted by said means to move on said piston assembly during longitudinal movement of said assembly.

RAYMOND W. JUSTICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Y Number Name Date 831,603 Davis Sept. 25, 1906 1,774,967 Ellis Sept. 2, 1930 2,038,092 Wheeler Apr. 21, 1936 2,225,140 Walker Dec. 17, 1940 2,493,782 Schwarz Jan. 10, 1950 FOREIGN PATENTS Number Country Date 487,335 Great Britain June 20, 1938 

